This is a little piece of Micro Music code:
; OUTPUT TO MSX-MUSIC -------------------------------------------------------
; IN: B=REGISTER, A=DATA
; OUT: NOP
; MOD: NOP
;
FMOUT: JR R8FMOUT ; ga uit van TURBO-R computer
PUSH BC
PUSH AF
LD A,B
LD BC,(FMPORT)
OUT (C),A
NOP
INC C
POP AF
OUT (C),A
POP BC
RET
FMPORT: DW 7CH
R8FMOUT:PUSH BC
PUSH AF
IN A,(0E6H)
LD C,A
FMOUT1: IN A,(0E6H)
SUB C
CP 6
JR C,FMOUT1
LD A,B
OUT (7CH),A
IN A,(0E6H)
LD C,A
FMOUT2: IN A,(0E6H)
SUB C
CP 1
JR C,FMOUT2
POP AF
OUT (7DH),A
POP BC
RET
INITFM: LD C,9
LD B,30H
INITFM1:LD A,0FH
CALL FMOUT
INC B
DEC C
JR NZ,INITFM1
JP INIPSG
The 'JR R8FMOUT'is self modifying.
The music player routines came from Micro Cabin's Princess Maker. In
the first
versions of Micro Music the player came from Xak-I.
Frits
PS. What do you know about port A7 ?
Laurens Holst wrote:
> The Turbo-R has a timer build in that is increased every 1 microsecond or
so.
> Maybe 2 or more microseconds, I don't known the exact value. And it did
> have something todo with I/O ports E5 / E6, or any number near these
numbers.I/O ports E5/E6... that's the timer of the MSX-MIDI. It also has another
timer used by the PCM play routines. However, it is only 2-bit or so...> All I know for sure is that when writing into the FM-PAC registers the
core code
> for playing music uses this timer to wait between two OUT
(port),register/value
> instructions. If the timer isn't increased than the whole program will
lock up.
>
> This behaviour is also implemented in my own TSR program Micro Music.Oh? What is it???
> The MSX2+ does not have this timer, by my knowledge.
Nope...
~Grauw
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